Gram-negative gliding bacteria associated with periodontal diseases will be fractionated and their exopolysaccharide, lipopolysaccharide, and peptidoglycan components purified, chemically characterized, and assessed for endotoxic activity. A separate group of seemingly novel gram-negative bacteria, also associated with periodontal tissues, will be characterized in terms of morphological and physiological traits as an aid in the identification of them, and representative members of subgroups fractionated and assayed as above. BIBLIOGRAPHIC REFERENCES: Enrichment culture approaches to the study of the oral microbiota; E. R. Leadbetter and S. C. Holt in Microbial Aspects of Dental Caries, 1976, in press. Abstract: Characteristics of Capnophilic gliding bacteria from the oral cavity; G. Forcier, S. C. Holt and E. R. Leadbetter. Ann. Meeting Amer. Soc. Microbiol., p. 122, 1976, in press.